[dragonwriter]

> English is not my first language but I think it was the host who introduced that term?

It was not.

Relevant portion of the transcript:

WALLACE: “Are you willing tonight to condemn white supremacists and militia groups…”

TRUMP: “Sure…”

WALLACE: “And to say that they need to stand down and not add to the violence in a number of these cities as we saw in Kenosha, and as we’ve seen in Portland”

TRUMP: “Sure, I’m prepared to do it, but I would say almost everything I see is from the left-wing not from the right-wing. I’m willing to do anything, I want to see peace…”

WALLACE: “Then do it, sir.”

BIDEN: “Do it, say it.”

TRUMP: “What do you want to call them? Give me a name.”

WALLACE: “White supremacists and right-wing militias”

BIDEN: “Proud Boys”

Trump: “Proud Boys, stand back and stand by. But I’ll tell you what, somebody’s got to do something about Antifa and the left.”

[retox]

WALLACE: “And to say that they need to stand down and not add to the violence in a number of these cities as we saw in Kenosha, and as we’ve seen in Portland”

[...]

Trump: “Proud Boys, stand back and stand by.

Trump parroted the language in the request by Chris Wallace and the named individuals from Biden. It was a gotcha request.

[dragonwriter]

> Trump parroted the language in the request by Chris Wallace

No, he didn't. And while he does have trouble focussing long enough to string together a full coherent sentence, he's not so incompetent with words and shirt phrases to not understand the difference with, or to a inadvertently swap, the terms with very different meaning “stand back”, and particularly “stand by” when intending to repeat “stand down”.

“stand down” means to demobilize.

“stand back” means to pause, usually for planning or emotional reflection.

“stand by” means to be ready for action or orders.